A body's immune cells, the neutrophils and macrophages that are known for their abilities to clear infection can generate reactive oxygen metabolites that destroy microorganisms and normal or neoplastic (cancerous) cells and modulate inflammatory responses.
Neutrophils can be activated as a response to inflammatory stimuli, bacterial infection and/or other membrane changes. As a result, they produce super oxide radicals such as: HOO., O2., and OH. Chloride ion (Cl−) at physiological concentrations of 100-150 mM is oxidized by H2O2, which is catalyzed by myeloperoxidase (an enzyme within the neutrophils) to form hypochlorous acid (HOCl) and HCl.
Physiological generation of HOCl is tightly regulated through feedback inhibition by an intricate network of biochemical signals. HOCl is generated at a concentration of 2×10−7 M per 106 activated neutrophils. This quantity of HOCl is estimated to kill approximately 150×106 E. coli bacteria. Once HOCl is produced, it degrades rapidly by reacting with multiple oxidizable substrates within the complex cell system. Thus, the concentrations of reactive oxygen-metabolites are expected to fall to undetectable levels within hours. However, it has been demonstrated that neutrophils can use their HOCl to generate large quantities of a rather long-lived oxidants, such as N-chloramines. These long-lived oxidants are generated as monochloramines of taurine (NCT, or N-chlorotaurine) and dichloramines of taurine (NNDCT, or N,N-dichlorotaurine) depending on the pH of the cellular environment. These oxidants are powerful antimicrobials and play key roles within the defense system as well as modulating the cytokines and growth factors in the host body.